'80 K20 Engine Question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

bpeters5814 · 11-17-2011, 12:53 PM

Hey all, I'm usually on the '88-'98 forum, but I've been looking for a 3/4 ton 4x4 square body for a long time. There's one coming up on an auction in about a month. The listing says "gas engine". I called the lady selling it, and she has no idea if it's a 350 or a 400. Is there an easy way to tell? And if it's a 400, what should I watch out for? Not too familiar with those. Thanks in advance.

lindstromjd · 11-17-2011, 02:49 PM

Just a little tip, 400's are opposite 350's when it comes to mains. The 2 bolt main 400's are stronger than a 4 bolt. I don't know anything about identifying one from the outside though...

Your41Plague12 · 11-17-2011, 08:04 PM

You'll have to pull a head off to verify it, unless you have a book of casting numbers. The heads have steam holes drilled in them, they're a totally different beast internally than a 350.

bpeters5814 · 11-18-2011, 12:31 AM

Alright, thanks guys. If it goes for the right price, I'll buy it regardless. I was just wondering.

Your41Plague12 · 11-18-2011, 02:07 AM

Either a 350 or a 400 will be a good engine. You mainly have to watch people swapping heads on a 400. They'll overheat easily if 350 heads are put on a 400 because of the lack of steam holes.

Keith Seymore · 11-18-2011, 08:48 AM

Also - if it's the original engine (if she can tell you it's never been changed) then it would be a 350.

A 400 cubic inch engine was not available in an 80 K20 Suburban from the factory.

K

tater502 · 11-18-2011, 08:36 PM

If its a 400 it will have a groove in the balancer. I dont know if they are all like that, but all the 400 balancers I've seen are.

rayfinseats · 11-18-2011, 09:36 PM

Some 400's have 3 softplugs on the sides vs. two.

**hatzie** · 11-19-2011, 07:35 AM

If it's the original V8 engine read the third VIN letter.
R 400
M or L 350
G 305
S 454

bpeters5814 · 11-19-2011, 09:42 AM

This is what they have down for the VIN: CKX24AJ137689

So... is that right? I tried using a VIN decoder and it didn't recognize it. I'm going to go look at it hopefully this week or the next, so I'll verify it.

Thanks all!

11-17-2011, 12:53 PM	#1
bpeters5814 Registered User Join Date: Apr 2008 Location: Worms, Nebraska Posts: 304	'80 K20 Engine Question Hey all, I'm usually on the '88-'98 forum, but I've been looking for a 3/4 ton 4x4 square body for a long time. There's one coming up on an auction in about a month. The listing says "gas engine". I called the lady selling it, and she has no idea if it's a 350 or a 400. Is there an easy way to tell? And if it's a 400, what should I watch out for? Not too familiar with those. Thanks in advance.

11-17-2011, 02:49 PM	#2
lindstromjd Gentleman Jim owner x2 Join Date: Oct 2010 Location: West Des Moines, IA Posts: 464	Re: '80 K20 Engine Question Just a little tip, 400's are opposite 350's when it comes to mains. The 2 bolt main 400's are stronger than a 4 bolt. I don't know anything about identifying one from the outside though... __________________ 1975 GMC Gentleman Jim #1 -357 / 700r4 1975 GMC Gentleman Jim #2 -350 / TH350

11-17-2011, 08:04 PM	#3
Your41Plague12 Registered User Join Date: Dec 2010 Location: Pittsburgh, PA Posts: 1,009	Re: '80 K20 Engine Question You'll have to pull a head off to verify it, unless you have a book of casting numbers. The heads have steam holes drilled in them, they're a totally different beast internally than a 350. __________________ Steve Member of the Foot Pedal Club '83 Chevy K20: 6" Rough Country, 3" Performance Accessories BL, Bushwacker Cutouts, 38x15.50 Mickey Thompson Baja Claws, 350 HP 350 crate engine from Jegs, Turbo 400

11-18-2011, 12:31 AM	#4
bpeters5814 Registered User Join Date: Apr 2008 Location: Worms, Nebraska Posts: 304	Re: '80 K20 Engine Question Alright, thanks guys. If it goes for the right price, I'll buy it regardless. I was just wondering.

11-18-2011, 02:07 AM	#5
Your41Plague12 Registered User Join Date: Dec 2010 Location: Pittsburgh, PA Posts: 1,009	Re: '80 K20 Engine Question Either a 350 or a 400 will be a good engine. You mainly have to watch people swapping heads on a 400. They'll overheat easily if 350 heads are put on a 400 because of the lack of steam holes. __________________ Steve Member of the Foot Pedal Club '83 Chevy K20: 6" Rough Country, 3" Performance Accessories BL, Bushwacker Cutouts, 38x15.50 Mickey Thompson Baja Claws, 350 HP 350 crate engine from Jegs, Turbo 400

11-18-2011, 08:48 AM	#6
Keith Seymore Registered User Join Date: May 2009 Location: Motor City Posts: 9,230	Re: '80 K20 Engine Question Also - if it's the original engine (if she can tell you it's never been changed) then it would be a 350. A 400 cubic inch engine was not available in an 80 K20 Suburban from the factory. K __________________ Chevrolet Flint Assembly 1979-1986 GM Full Size Truck Engineering 1986 - 2019 Intro from an Old Assembly Guy: http://67-72chevytrucks.com/vboard/s...d.php?t=342926 My Pontiac story: http://forums.maxperformanceinc.com/...d.php?t=560524 Chevelle intro: http://www.superchevy.com/features/s...hevy-chevelle/

11-18-2011, 08:36 PM	#7
tater502 Registered User Join Date: Sep 2010 Location: Rio, Il Posts: 38	Re: '80 K20 Engine Question If its a 400 it will have a groove in the balancer. I dont know if they are all like that, but all the 400 balancers I've seen are.

11-18-2011, 09:36 PM	#8
rayfinseats Registered User Join Date: Dec 2010 Location: sioux city, iowa Posts: 619	Re: '80 K20 Engine Question Some 400's have 3 softplugs on the sides vs. two.

11-19-2011, 07:35 AM	#9
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,977	Re: '80 K20 Engine Question If it's the original V8 engine read the third VIN letter. R 400 M or L 350 G 305 S 454

11-19-2011, 09:42 AM	#10
bpeters5814 Registered User Join Date: Apr 2008 Location: Worms, Nebraska Posts: 304	Re: '80 K20 Engine Question This is what they have down for the VIN: CKX24AJ137689 So... is that right? I tried using a VIN decoder and it didn't recognize it. I'm going to go look at it hopefully this week or the next, so I'll verify it. Thanks all!



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